[Exim] Rejecting Email with bad sender MX

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Author: Rick Ballard
Date:  
To: exim-users
Subject: [Exim] Rejecting Email with bad sender MX
Lately I have been seeing spam with such DNS oddities as
MX=127.0.0.1 or MX=192.168.1.1. This is obviously purposely
misconfigured.

How can I just kill this junk on sight ? I want
to fail incoming mail based on the sender's MX
record.

--------------- Example 1

MX points to 192.168.1.1

2001-02-06 08:48:30 14Q6e2-00002E-00
misdirected.buydomains.com [192.168.1.1]: No
route to host

mail1:~$ nslookup                 

> set type=mx
> accessmaster.com

accessmaster.com        preference = 0, mail
    exchanger = misdirected.buydomains.com
accessmaster.com        nameserver =
    ns.buydomains.com
misdirected.buydomains.com      internet address
    = 192.168.1.1
ns.buydomains.com       internet address =
    207.32.91.110


--------------- Example 2

MX points to 127.0.0.1

2001-02-03 20:24:51 lowest numbered MX record
points to local host: giveaway.com (while
verifying <justforyou@???> from host
(anydomain.com) [154.5.39.84])

mail1:~$ nslookup                 

> set type=mx
> giveaway.com

giveaway.com    preference = 20, mail exchanger 
= mail.giveaway.com
giveaway.com    nameserver = 
dns.fastdnsservers.com
giveaway.com    nameserver = 
dns2.fastdnsservers.com
mail.giveaway.com       internet address = 
127.0.0.1




--
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Rick Ballard            Rick.Ballard@???
Halifax, Nova Scotia, Canada    http://www3.ns.sympatico.ca/Rick.Ballard